1. Field
The subject matter disclosed herein relates to electronic devices, and more particularly to methods and apparatuses for use in route navigation involving a mobile station.
2. Information
The Global Positioning System (GPS) and other like satellite positioning systems have enabled navigation services for mobile handsets in outdoor environments. Since satellite signals may not be always be reliably received and/or acquired in an indoor environment, different techniques may be employed to enable position estimation and related navigation services. For example, mobile stations can typically obtain a position fix by measuring ranges to three or more terrestrial radio transmitters, which are positioned at known locations. Such ranges may be measured, for example, by obtaining identifying information (e.g., a MAC ID address, etc.) of such access points and measuring one or more characteristics of signals received from such access points such as, for example, signal strength, round trip delay, just to name a few examples.
By way of additional example, a mobile station, such as, a mobile phone, smart phone, etc., may perform signal-based position estimation to identify its location within a structure by taking measurements, for example of a signal strength (e.g., an RSSI) and/or propagation time (e.g., a round-trip time (RTT)) for signals exchanged with various radio transmitters (e.g., access points, beacons, etc.). A mobile station may use these or other like measurements to obtain a probability distribution over a region of space (e.g., defined using two or coordinates (x, y), etc.). Such a probability distribution or other like information may, for example, be used in a particle filter, Kalman filter, and/or other positioning mechanism using known techniques.
In some implementations, an indoor navigation system may provide a digital electronic map to mobile stations, e.g., as a user enters a particular indoor area. Such a map may show indoor features such as doors, hallways, entry ways, walls, etc., points of interest such as bathrooms, pay phones, room names, stores, etc. Such a digital electronic map may be stored at a server to be accessible by a mobile station through selection of a URL, for example. By obtaining and displaying such a map, a mobile station may overlay a current location of the mobile station (and user) over the displayed map to provide the user with additional context. Using map information indicating routing constraints, a mobile station may also apply location estimates to estimating a trajectory of the mobile station in an indoor area subject to the routing constraints.
In some particular applications, a navigation system may specify routes to a destination. For example, a mobile station application may receive a user input specifying a destination and the application may determine a route. The route may then be overlaid on a displayed map and/or provided as a sequence of instructions (e.g., walk a certain distance, make a left turn at a particular sign or point of interest, etc.). In determining a route, such an application may apply anyone of several techniques for determining an “optimal” route based upon predefined criteria. For example, such techniques may employ Dijkstra's algorithm or other graphical techniques to determine such an optimal route.
Graphical techniques for determining an optimal navigation route typically do not consider barriers or “bottlenecks” which may impede or delay a traveler along such a navigation route. As such, if reducing or minimizing travel time along a route and/or estimating an accurate transition time or time of arrival is of importance to a traveler, such graphical techniques may not provide the desired result.